Photoacoustic microscopy (PAM) has been used in recent years to satisfy a need in high-resolution imaging of endogenous optical absorption contrasts in vivo, among which DNA/RNA, hemoglobin, and lipid may be of particular interest. Specifically, a cell nucleus may be a critical organelle containing DNA genome, which strongly absorbs ultraviolet light. Additionally, morphological changes in cell nuclei, including enlargement and envelope folding, are considered hallmarks of cancer cells.
Hemoglobin, a dominant absorber in the visible spectral range, is the primary oxygen carrier in the blood circulation. Angiogenesis and hypoxia, which can be respectively revealed by the distribution and oxygen saturation of hemoglobin, are also core indicators of cancer. Further, lipid forms a diverse group of infrared-absorbing molecules that play important roles at cellular and organismal levels. Aberrant lipid metabolism therefore can establish hallmarks of cancer cells.
Concurrent imaging of the multiple endogenous optical absorbers at the same spatial scale may be promising for both basic and translational cancer research. However, multispectral PAM modalities with ultraviolet to near-infrared spectral ranges have been difficult to implement in practice due to complications caused by the chromatic aberration of the optics. It is with respect to these and other considerations that the various embodiments described below are presented.